Today Sonatype has introduced Nexus: a Maven Repository Manager.
Brian Fox’s blog entry Introducing Nexus contains a number of useful links.
“Enough talk, click on over to the Nexus site where you can find more information and the download link. We’d love to hear from you on our user list and on irc.codehaus.org #nexus. Also be sure to visit our Maven book, which contains a Nexus chapter.”